Description
There is a well-known method to describe personality, which is MBTI(Myers-Briggs Type Indicator).
One day, TAs of I2P(I) want to develop their own TI, which is called "HUTI".
We'll use a integer to record the index of each personality type.
To check which type is the most unique one, given a type sequence, the most unique one is the one with an odd number of occurrences
For example, the unique number in [1, 3, 2, 3, 2] is 1.
Following the above rule, we'll check N students and the results will be used to determine the most unique type in the class.
Note:
Use an "XOR" operation in this problem.
If you need more details, you can check : this
Input
The input is composed of two parts.
The first line is N (1<=N<=100000001).
The following N lines will be the type indexes (The integer will be less or equal to 100000000).
Output
The unique type ended with a new line character.